The correct order of the atoms in terms of their `IE_(1)` is :

Options

A. `Li lt B lt Be lt C`
B. `Li lt Be lt B lt C`
C. `Li gt B gt Be gt C`
D. `Li gt Be gt B gt C`

Explanation

Generally `IE_(1)` increases along the period `(rarr)`, i.e. `IE_(1)` of `2nd` period should be `Li lt Be lt B lt C`. But there is an exception in the `IE_(1)` values of `Be` and `B`, i.e. `IE_(1)` of `B lt IE_(1)` of `Be`, due to penetration effect.
Hence, the answer is `(i)`, i.e. `Li lt B lt Be lt C`.